This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 13 |
| 5 | 28 |
| 6 | 127 |
| 7 | 376 |
| 8 | 1522 |
| 9 | 5210 |
| 10 | 20403 |
| 11 | 74952 |
| 12 | 292313 |
| 13 | 1114704 |
| 14 | 4371839 |
| 15 | 17040586 |
| 16 | 67378981 |
| 17 | 266402370 |
| 18 | 1061919289 |
| 19 | 4241539218 |
| 20 | 17030430061 |
| 21 | 68554148388 |
| 22 | 276988107861 |
| 23 | 1121954081852 |
| 24 | 4557637048543 |
| 25 | 18556386241468 |
| 26 | 75729621399950 |